In recent years, with regard to ultrasonic flaw detection and ultrasonic diagnosis that are one sort of nondestructive inspection, transverse ultrasonic waves have been used in the majority of instances owing to their favorable detection sensitivity. In the case of carrying out the inspection, a highly viscous transmission medium is used between a test specimen and a probe for the purpose of enhancing the transmission efficiency, wherein polyglycerol and polypropylene glycol are known as a transmission medium.
However, the above-mentioned transmission media are problematical in high hygroscopicity causing rust acceleration in a test specimen after use, decrease in the transmission efficiency during use and the like. Under such circumstances the development of a transmission medium with low hygroscopicity has eagerly been desired.
In addition, the conventional polyglycerol and polypropylene glycol have been insufficient in adhesivity to a solid called thixotropics, thereby taking 2 to 3 minutes in sticking and film stabilization. It being so, from the viewpoint of enhancing inspection efficiency and the like, there has been sought for a transmission medium capable of measuring immediately after the coating thereof, that is, a transmission medium having favorable adhesivity to any solid.
Moreover, the aforesaid conventional transmission media are problematical in that it is incapable of transmitting transverse ultrasonic waves in the measurement in a non-contact state in which a test specimen and a probe are immersed therein. Thus it has been hoped to develop a transmission medium capable of transmitting transverse ultrasonic waves even in a non-contact state.